The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
The flow and flow rate of tissue and fluids through an aspiration tube is of interest during operations, including ophthalmic operations. Measurement of the surgical aspiration flow rate may be valuable in that it can provide for safe control of the ophthalmic surgical equipment. In most positive displacement-based systems, flow has been known to be inferred from the cycle frequency, i.e., the rotation rate, of the aspiration pump. However, this inference may be invalid in situations where there are varying pressure differentials within the pump system. The pressure variations may occur as a result of changes in the irrigation-fluid bottle height, changes in the viscosity of the aspirant, and changing occlusion conditions at the distal end of the aspiration tube. For known commercially available vacuum-based aspiration systems no flow measurement has previously been feasible, nor can flow be accurately inferred from the vacuum level. This is because the actual flow rate varies with the viscosity of the aspirant and the occlusion state of the aspiration tube. Thus, direct measurement of the flow rate is difficult to achieve and typically, impractical for vacuum-based systems.
Therefore, it would be desirable to have a viable, low-cost flow sensor that could be inexpensively incorporated into a disposable or reusable system to directly measure flow rate. Such a flow measurement can enable new modes of operation, particularly for vacuum-based systems.